


back to a time only we knew

by yunnings (ladylolli)



Series: free! mer!AU collection [2]
Category: Free!
Genre: Childhood Memories, M/M, Mentions of Haru - Freeform, Mer!AU, Momo cameo, Multi, One-Sided Relationship, PWP without Porn, angst/pain/hurt, merchild!Rin, nagigou if you squint
Language: English
Status: Completed
Published: 2015-12-31
Updated: 2015-12-31
Packaged: 2018-05-10 05:31:42
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,004
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5572741
Author URL: https://archiveofourown.org/users/ladylolli/pseuds/yunnings
Summary: <blockquote class="userstuff">
              <p>prompt: Sousuke → Rin, Seaside, Painful, 10 Years Later</p><blockquote>
  <p><i>“Maybe if you walk along the beach,” </i>like now<i> - Rin begins, “you’ll get to see mermen.” </i>And me<i> goes unsaid. Their sandaled feet crunch against damp sand.</i></p>
  <p> </p>
  <p>    <i>Sousuke glances at the vast sea to the rocky outcrops. “Mermen?” he pauses, doubtfully questions his friend, “Not mermaids?” A mischievous light glints in his eyes when he looks at Rin, “Not merchildren?” Sousuke teases, taking off down the coast to an airplane’s roar.</i><br/></p>
</blockquote>
            </blockquote>





	back to a time only we knew

**Author's Note:**

  * For [knaire](https://archiveofourown.org/users/knaire/gifts).



> 1/∞ fics I owe you: a sidefic to _that_ nonexistent mainfic /coughs
> 
> beta credits: [rikotan](http://archiveofourown.org/users/rikotan/pseuds/rikotan)  
> thank you for betaing and lending knowledge of free!verse to this 3k monster! any remaining mistakes are mine.
> 
> p.s., jes said _"HER DoM IS COMING OUT”_ + _“HAPPY ~~FUCKING~~ NEW YEAR YOU DoM”_

The bell rings. “Where are you going?” Rin leans back from his seat. Sousuke moves to collect his books while keeping Rin’s head at a distance. Hindered, Rin sits uprights and turns to face him. “Later, I mean”.

He gives a noncommittal sound.

“Well?” Rin raises his eyebrows in prompt. Sousuke pauses in slotting books into his bag, stares Rin head-on, stubborn, “Jogging.”

“By the beach?” His friend judges, raising both eyebrows. A sly, smug leer is playing on his lips. This is why Sousuke does not want to tell Rin. He injects as much aggravation as he is feeling into the sigh regardless, “Yes.”

When Rin guffaws, Sousuke grumbles, “I jog there _every day_. You know that. Everyone in Samezuka knows that. Stop laughing.” - _at the habits_ you _had me cultivate since young_ , he grouses silently. Sousuke’s gaze drop as he continues moving books into his bag. Reluctantly, he asks “Wanna join?”

Rin punches his shoulder and grins wide. Sousuke expertly hides the wince. Rin’s eyes, pleased and smug, said _I knew you missed me_. Sousuke rolls his eyes. Brain juices sapped from class, Sousuke doubts he will have enough discipline to hide another bitter smile.

_-_

_Sousuke does not say 'I miss you'. Instead, he says, “Good luck” and “I’ll support you from Japan”. It is for Rin’s good; Rin is moving because it is a choice he made. They walk along the beach, Sousuke holding Rin's hand tight._

_“Maybe if you walk along the beach,”_ like now _\- Rin begins, “you’ll get to see mermen.”_ And me _goes unsaid. Their sandaled feet crunch against damp sand. Occasionally, seawater soak their shoes, lapping their feet with seawater and depositing grainy sand when the waves flow strongly._

_Sousuke glances at the vast sea to the rocky outcrops. “Mermen?” he pauses, doubtfully questions his friend, “Not mermaids?” A mischievous light glints in his eyes when he looks at Rin, “Not merchildren?” Sousuke teases, taking off down the coast to an airplane’s roar._

_“Hey!” Rin protests; chasing his companion along the beach._

_Sousuke hollers back, deftly swerving along the coast as if playing catch with the lapping waves, “The waves are lava!” Rin grins, skilfully avoiding the waves, fired up at their impromptu game of chase._

_-_

Rin had grabbed onto Sousuke before he realises. His form and expression victorious. Sousuke tugs him up as their next swimmer dives in, “Congrats.” They can hear Momotarou’s raucous  cheering in the background.

“I did well, didn’t I?” Rin gloats. He sputters on choked air before he continues, “I knew I did.” Sousuke pats his back, silently muttering ‘breathe’ before showing the stopwatch to his friend. “A good record,” Sousuke agrees, blasé. He does not want to think to whom that Olympic-appropriate triumphant beam belonged to. _(Iwatobi’s Haruka Nanase)_

Rin scowls when he wipes himself dry, sharp teeth peeking and challenging eyes taunting behind the towel. “Just good?” He gestures to the stopwatch with a huff, “That’s my best record yet! Let’s see how well _you_ do then.”

Sousuke retrieves the towel, passing it to their frightened manager with an apologetic smile. “We’re not even swimming with the same style,” he voices simply, despite beginning warm-up.

“We’ll race with our strengths,” Rin rephrases. Sousuke wonders if Rin swimming freestyle is considered a strength, when freestyle stemmed from Rin’s obsession with Iwatobi’s Nanase. He strokes where his heart is and does not mention that Rin’s specialty is butterfly, just like his. Rin continues, “It’ll be the same thing.”

Sousuke shrugs, expression schooled while weighing between swimming butterfly or freestyle.

“So are you up for it?” Rin’s hand is on his hips; _challenging,_ Sousuke notes. He is fired up too, over their impromptu race. Sousuke smirks tauntingly as he stretches out his arm muscles, especially careful of his left shoulder. _Butterfly it is_ , Sousuke decides. “Eat your words.”

Rin returns a taunting grin of his own, “Prove it.”

 _-_  

_Rin is bashing buttons, feet flying and elbows occasionally hitting Sousuke’s ribs. Sousuke dodges, calmly pressing buttons. The game ends 8-2 with Sousuke winning. Rin groans into his knees, “I still can’t win with fouls.” Sousuke unconsciously rubs his abused ribs that Rin had managed to hit earlier. Since Rin is fouling on purpose, he lets the topic drop._

_“Those big movements don’t help, you know.” Sousuke tells Rin._

_Rin glowers. “Let’s go one more round!” He demanded, eyes alight and limbs splayed out. Sousuke critically looks at Rin’s limbs and shifts further away. “Are you going to foul-hit me again?”_

_“Yeap!” Rin grins toothily, “It bought me those 2 points earlier.”  Sousuke sighs and presses [start] to Rin promising a surprise comeback win._

_The game is 4-1 in Sousuke’s favour. 5 more rounds to go._ Maybe I should let Rin win 2 or 3 rounds _, Sousuke surreptitiously peeks at his friend’s focused figure. His attention slips back to his character when Rin’s character managed to land a powerful hit._

_“You know,” Rin begins, mashing buttons with less vigour._

_“Mm?”_

_“I’m going to move soon.”_

_“Move?” Their characters are hitting air._

_“Yeah,” Rin seconds, “To Australia.”_

_Sousuke presses [pause]. "Is this a tactic for your 'surprise comeback win'?" He puts the controller down to hide his shaking hands._ Please say it is _, Sousuke prays. His heart hammers against his chest when he looks at Rin's face, "Is this for real?"_

_"Yeah," Rin bites his lips. The choked guffaw that spills out of his lips sounds breathless. "This–" Rin gestures to his reaction, "wasn't what I expected."_

_Sousuke was sitting up straight now. "It's true then," Sousuke says in Rin's stead._

_"Come on," Rin moves closer to punch his shoulder, “Lighten up! It’s not today or tomorrow. Anyway, I’ll be enrolled in a sports school for competitive swimming there. Maybe you'll see me on TV!” When he returns to his seat, languid limbs at odd with the mischievous glimmer in his eyes, Rin is himself battling Sousuke on Alley Fighter, "Damn. I was hoping to use that fact to win."_

_Rin wins 6-4._

_"I hope your win feels bitter." Sousuke grumbles, "What an underhanded tactic."_

_Rin was sparkling, no hint of bitterness nor remorse on his countenance. He shoves into Sousuke's space, crowing, "Still a legit win!"_

_Sousuke wonders if winning will become an unforgettable memory._ Probably not _, he ruefully realises. "So?" Sousuke begins, "What reward do you want for -” he raises his fingers to quote, “- ‘beating the unbeatable’?"_

_"Come on," Rin pulls his friend up. "My reward will be to teach you to swim!” He gestures proudly to his chest, “Let's go swim!" Sousuke does not mention that he had his father teach him, before, in a bid to be closer to his friend._

_-_

Sousuke later buys Samezuka’s specialty, limited, overpriced lunch for a glowing Rin. He is humming his own rendition of Queen’s ‘We are the champion’ under his breath, cheekily whispering ‘I am the champion’ instead of the actual verse whenever it comes up.

Sousuke rolls his eyes.

“Try and try again,” Rin says between mouthfuls, “It’s why I keep swimming freestyle - to beat Haru.” Sousuke knows, Rin shared this with him. Still, his heart almost leaped out of his mouth. He had trudged through school without Rin mentioning Nanase once, until now. Phantom pain shoots up his shoulder in line with Nanase’s name. Unbidden, he rubs his shoulders. _I can’t swim after high school_ remains a secret; he does not blurt out _I can’t keep trying, unlike you._ Resentment burns his tongue, _Unlike Nanase_.

Sousuke wills his heartbeat to slow. Rin continues, “It’s how I beat you at Alley Fighter all those years ago - persistence.” He finishes with a flourish that warrants being beaten up by his listener(s).

“You did not,” Sousuke glumly bites out while stealing a spoonful of Rin’s lunch, too tired for his heart to soar that Rin remembered playing Alley Fighter in his bedroom. “You cheated.”

“Still a legit win!” Rin chokes on the rice while laughing, oblivious to Sousuke’s slip-up.

When Sousuke ensures Rin does not asphyxiate to death's door, he focuses on his meal to contain bittersweet fondness. This is the Rin he knows from childhood: tireless and determined, just like the silly memories unique only to the both of them.

_-_

_Sousuke clambers over a particularly big rock beyond the shallow pool. There is silver glinting just out of hand's reach. He is entranced. When he briefly touches the spot to find nothing, Sousuke huffs while eying the silver spot._

_Rin looks critically at the boy wading around his shallow pool. Nonchalantly, he surfaces from the water, "I've never seen you around." The trespasser whips around in surprise, accidentally flinging a hermit crab to his face. Rin scowled._ Rude _. Mentally, Rin takes off 20 points for the new boy’s intrusion, and another 30 points for hitting him._ A whopping -50 points _, Rin frowns gravely, patting the stinging cheek,_ what a terrible first impression _._

_Sousuke winced before catching himself. Palms raised in surrender, he apologised, weakly adding “I didn’t mean to.” His companion looks red - redder - with the mark he had accidentally left. Warily, he approached the rocky outcrops where red boy is resting on. “Are you alright?”_

Curiouser and curiouser _, Rin muses. Being apologised to - and not having to apologise, a first to Rin - warrants generously removing the -50 points he had given earlier. It is nice not to be in the wrong._

Also _, Rin decides,_ having a friend is more fun than being alone underwater _._

_With a flick of his tail, he grins at the new boy. His face still stung when he grins. Sousuke gasp at the sight of fins. Rin might have puffed his chest out in pride and excitement that his maybe-friend noticed. He bites his lips from shouting ‘Yes, I’m a merman!’_

_"Let's play," Rin one-sidedly entreats, turning somersaults underwater, "Catch me if you can!"_

_Sousuke leans to catch the briefest glimmer of scales._ Fins! _he realises, leaning further out, only for his limbs to slip on slimy algae. Sousuke falls headfirst into water, choking on saltwater._

_Alarmed, Rin rolls upright and silently swears under his breath. The new kid is knocked cold by the rocks and sinking fast. He shoots down after him._

 

_"Wake up," Rin laps seawater with his tail, dumping them on the unconscious boy. "Please," he adds as an afterthought. The boy sputters awake with a groan. Rin dives to hold the boy. "Why didn't you say you can't swim! That was dangerous!"_

_Sousuke has himself a faceful of red. He blinks and holds the boy at arm's length. Now that he is shocked awake now, Sousuke remembers his manners. "Who're you." He crawls to sit, wincing at the dizzy wave. He closes his eyes._

_"Sorry," his companion moves back, "you hit your head."_

_"Oh." That explains the dizzy spell. Gingerly, Sousuke touches the spot where he had hit himself._

_Rin seconds it, and asks suspiciously, "Are you okay now? I don't want to be arrested for unintentional murder."_

Murder – what? _Sousuke unconsciously shuffles backwards. His companion laughs. "Okay," red boy breathes, Sousuke spots his tail –_ tail; what? _His heart stutters and jumpstarts again._ I wasn’t dreaming _, Sousuke dazedly thinks_ , was I? _He longs to reach out and physically touch red boy’s tail but keeps his hands tightly clenched to his side. He is not going to drown again. "I see you're alive and alright now. Gosh, I was so worried."_

_"Who are you. What are you?" Sousuke attempts, squinting at where red boy's tail was earlier instead. He catches himself, "I'm Sousuke. Just moved here." Red boy brightens._

_"Hey new neighbour," Rin grins with a mock-salute, "I'm Rin and I'll see you later okay?" He swims further past the rocky outcrop, waving and hollering, “I’ll explain everything later!”_

_Sousuke nods._ Okay. _Weakly waves back. He stares blankly as Rin pops beneath the waves. Cautiously, he leans past the rocky outcrop._ He isn't dreaming, is he?

 

 _“Who’re our neighbours?” Sousuke takes his seat during dinner. His mother smiles when she brings over the dishes. “The Matsuokas,” she answers, “If I remember correctly, they’ve a boy your age.”_ Matsuoka Rin, _Sousuke registers the boy’s name when he chews dinner,_ the same age.

_Later, when she cleans the dinner table, Sousuke hears his parents talking. “It’s good that Sousuke’s adapting to the new environment,” Sousuke wills the happy grin down at his father’s approval. His mother agrees happily in the background, “I hope he makes friends.”_

_“Okay, I will.” Sousuke silently mouths the words towards the kitchen. "Good night." He will make his parents proud._

 

 _Sousuke catches glimpses of Rin in and around town._ Legs _, he observes each time,_ maybe I did hallucinate the tail. _Regardless, Sousuke gnaws at his lips when he had unconsciously caught sight of Rin. Rin’s ‘I’ll explain everything later’ becomes ‘I’ll explain everything never’. So much for making new friends. With contemptuous vigour, he redirects his attention onto selecting budget-appropriate snacks._

 

_“Later is now!” Rin insists the next time Sousuke wade around the shallow pool, complaining that Rin had not kept his promise. Sousuke gave up pursuing the topic. “Will you explain everything now?” He huffs a long-suffering sigh._

_Rin laughs. “Give me a sec to,” he waves his hands in circles, “collect my thoughts? I don’t know where to start.”_

_Sousuke sighs acquiescence, eying the red tail._ It wasn’t a hallucination _, Sousuke belatedly realises, then tracks back,_ maybe the boy I saw wasn’t Rin? _The boy he saw had legs. A doppelganger? Sousuke shoots Rin-the-merchild a look, is he going to die? There’s a doppelganger in town…_

_Sousuke groans, his head hurt. “Why don’t you ask and I answer?” Rin quickly appeases with palms out._

_“Too many questions -”_

_“That’s good!” Rin sparkles, face open._

_Sousuke coughs at the interruption, “Too many questions that I don’t know where to start.”_

_“Oh.” Rin is already floating away, arms cushioning his head._ Don’t go, _Sousuke thinks, reaching to grab onto his companion when Rin fumbles to push Sousuke back against the rocky outcrop. “What are you doing?” He growls, “You almost drowned the last time!”_

_“You were gonna dodge explaining to me again!” Sousuke retorts._

_“I wasn’t!”_

_Sousuke glance at his companion suspiciously. He lets his hands fall and scrambles backwards until Rin makes a satisfied noise. He bites down on the ‘happy now?’ and asks instead, “Is that really a tail?”_

_Rin flicks water into the shallow pools with his tail fin, wetting Sousuke. “Yeap.” There is a proud grin on his face. “I’m what you call a merman.” Before Sousuke can ask, Rin is shoving it in Sousuke’s face, “If you don’t believe me, wanna touch it?”_

_Stroking the tail seem to sooth tensions. Unbidden, Sousuke slips, “I think I might’ve seen your doppelganger. Except with legs.” Rin’s salmon pink fin brushed past Sousuke’s face. His expression was rueful, “Actually, that’s me.” Sousuke cheers internally -_ That meant Rin saw me too! - _but schools his expression._

_“I don’t know how merman-ing works but,” Rin gingerly places his tail on his companion’s lap, “I’m human? And can become a merman if I dive deep enough?”_

_Rin breathes, relieved, when Sousuke seems to accept his half-assed answer. “Are we friends?” Sousuke peeks shyly up._

_Rin almost hit him on the chin when he whoops. “Rin. Matsuoka Rin. At your service,” Rin mirthfully introduces himself._

I know. _“I’m Yamazaki Sousuke. Nice to meet you, again.” Sousuke bites his cheeks, but the grin still spills pass his expression._

-

Before the door clicks open, Sousuke interrupts, “Did you see your sister?” Rin raises an eyebrow at his roommate.

“Yeah?” Sort of. He had waved to, pestered, and separated Nagisa from Gou - in that order - before heading to the beach with Haru. Rin moves to place his bag on their study table, peering curiously at Sousuke’s hunched form on the bottom bunk. “What’s up?” He does not question Sousuke’s presence on his bunk; they had known one another for too long, are too close, for formal lines cutting the room in half.

Sousuke stops scrolling down the app feed on his phone and looks at Rin. “What about,” Sousuke swallows his jealousy down, “Iwatobi’s Nanase.”

Rin sparkles, “Oh! I didn’t tell you, but I was with Haru.” Sousuke wills himself not to fiddle at his phone, typing phantom messages to phantom people or checking for nonexistent notifications. Instead, he puts it aside and starts a conversation. He does not ask what they did, given that Rin had not shared, instead, “How did it go?” His heart clenches painfully; it is lonely to be left out, even when they share 228ft2 of living space. This is not about him, this is about Rin.

“It was fun!” his companion chirps from his seat.

“That’s good,” Sousuke smiles. Shrinking further against the wall, he teasingly explains, “Nanase’s good for you.”

“Hey!” Rin protests with a sentimental grin, “It’s _me_ that’s good for him.” Sousuke does not think of the memories flitting behind Rin’s smile that he has no part in. _Australia,_ Sousuke only knows this, _and nothing else_. He wills down the knot of bitterness at being an outsider.

Rin stretches, as agile as a cat. “As expected, the sea is really nice.” Rin is looking at his feet and Sousuke knows he meant merman-ing. “Did you know?” Rin gushes, “Haru really has the prettiest shade for his tail. They’re like the sea we see from the coast.” Sousuke tries to imagine it, only dredging up images of reds that turn fiery orange under the sunlight.

“Yours look like koi fish,” Sousuke jokes, half hoping Rin catches on to even 0.01% of his feelings. He raises Rin’s pillow to shield from the flying book. “I’m joking,” Sousuke hugs the pillow, thinking of Rin’s merman life that Nanase is privy to, but he is not. “I don’t really know what yours looks like. It’s unique.” He finishes lamely, self-deprecating smile on his face.

The conversation drops along with Sousuke’s stomach when he knows Rin is thinking of Nanase again. Their distance widens.

 

**Author's Note:**

> update 050816: [mainfic](http://archiveofourown.org/works/7676779/chapters/17485477) up woop


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